Method of manufacturing organic light emitting diode arrays and system for eliminating defects in organic light emitting diode arrays

ABSTRACT

A method for manufacturing an organic light emitting diode (OLED) array is provided that includes applying an energizing signal to at least one of the OLED pixels in the array. The energizing signal exceeds a threshold level. The method also includes reducing the energizing signal and identifying an OLED in the array that continues to remain energized. The method further includes irradiating the identified OLED to degrade the organic material in the OLED. A method of performing quality control in a manufacturing process of an OLED array is provided. The method includes determining an intensity, a time and a wavelength of radiation sufficient to render an OLED of the OLED array inoperative by degrading organic material in the OLED. A system of performing quality control in a manufacturing process of an OLED array is provided. A computer-readable medium having stored thereon computer-executable instructions is provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/278,437 filed Oct. 7, 2009, which is incorporated herein byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to organic light emitting diode (“OLED”)devices. In particular, the present invention relates to a method andsystem for manufacturing OLED devices that degrades individual defectiveOLED pixels in the OLED device.

2. Description of Prior Art

An OLED device typically includes a stack of thin layers formed on asubstrate. In the stack, a light-emitting layer of a luminescent organicsolid, as well as adjacent semiconductor layers, is sandwiched between acathode and an anode. The light-emitting layer may be selected from anyof a multitude of fluorescent organic solids. Any of the layers, andparticularly the light-emitting layer, may consist of multiple sublayers.

In a typical OLED, either the cathode or the anode is transparent. Thefilms may be formed by evaporation, spin casting, other appropriatepolymer film-forming techniques, or chemical self-assembly. Thicknessestypically range from a few monolayers to about 1 to 2,000 angstroms.Protection of OLED against oxygen and moisture can be achieved byencapsulation of the device. The encapsulation can be obtained by meansof a single thin-film layer situated on the substrate, surrounding theOLED.

High resolution active matrix displays may include millions of pixelsand sub-pixels that are individually addressed by the drive electronics.Each sub-pixel can have several semiconductor transistors and other ICcomponents. Each OLED may correspond to a pixel or a sub-pixel, andthese terms are used interchangeably herein.

OLED pixels have a threshold energizing signal at which point they turnon, and begin to emit light. As the energizing signal falls below thethreshold level, a correctly operating OLED ceases to emit light. Duringthe manufacture of an OLED device including an array of OLED pixels,disturbances or contamination may cause one or more OLED pixels to notoperate properly. Due to processing issues or contamination, a fewsub-pixels can remain on irrespective of the driving conditions. Inparticular, some OLED pixels may continue to emit light after theenergizing signal has fallen below the threshold level. These defectivesub-pixels, also called inoperative OLED pixels, may also be calledstuck-on pixels or stuck-on OLED pixels.

In many applications the stuck-on sub-pixels are very undesirable, whichmay result in a zero tolerance for stuck-on sub-pixels. Out of millionsof sub-pixels in a display it is typically very difficult to obtain adisplay with zero stuck-on pixels or sub-pixels. One or more stuck-onOLED pixels may compromise an entire array of OLED pixels, andconventionally may require that the entire array to be discarded.

BRIEF SUMMARY OF THE INVENTION

A method to selectively identify stuck-on sub-pixels and eliminate themis provided. The method may be particularly suited to performance earlyin the production process for an OLED array to thereby reduce oreliminate unnecessary processing costs, by for instance identifying OLEDarrays that may not be able to be repaired.

A method for manufacturing an organic light emitting diode (OLED) arrayincluding OLED pixels is provided that includes at least partiallyforming the OLED array. Each OLED pixel in the OLED array includesorganic material and is responsive to an energizing signal exceeding athreshold level to energize the particular OLED pixel. The methodincludes applying the energizing signal to the OLED pixels in the array.The energizing signal exceeds the threshold level. The method alsoincludes reducing the energizing signal applied to the OLED pixels belowthe threshold level, and identifying a stuck-on OLED pixel in the arraythat continues to remain energized after the signal is reduced below thethreshold level. The method further includes irradiating the stuck-onOLED pixel to degrade the organic material in the stuck-on OLED pixel.

A method of performing quality control in a manufacturing process of anorganic light emitting diode (OLED) array including OLED pixels isprovided. The method includes determining intensity, a time and awavelength of radiation sufficient to render an OLED pixel of the OLEDarray inoperative by degrading organic material in the OLED pixel. Thedetermining operation is based on at least one of a first degradabilityof the organic material, a first absorption spectrum of the organicmaterial, a second degradability of at least one surface layer of theOLED array, and a second absorption spectrum of the at least one surfacelayer of the OLED array. The method also includes identifying a stuck-onOLED pixel of the OLED array, and exposing the stuck-on OLED pixel tothe radiation at the determined intensity, the determined time and thedetermined wavelength.

A system of performing quality control in a manufacturing process of anorganic light emitting diode (OLED) array including OLED pixels isprovided. The system includes means for applying an energizing signal tothe OLED pixels in which the energizing signal exceeds a thresholdlevel. The method further includes means for reducing the energizingsignal applied to the OLED pixels below the threshold level, and meansfor identifying a stuck-on OLED pixel of the array of OLED pixels.Furthermore, the system includes means for irradiating the stuck-on OLEDpixel to degrade the organic material in the stuck-on OLED pixel.

A computer-readable medium having stored thereon computer-executableinstructions is provided. The computer-executable instructions cause aprocessor to perform a method when executed in which the method performsquality control in a manufacturing process of an organic light emittingdiode (OLED) array including OLED pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an OLED array and a testing device during atesting procedure in accordance with an exemplary embodiment;

FIG. 2 is a plan view of the OLED array and the testing device of FIG. 1after performance of a method in accordance with an exemplaryembodiment;

FIG. 3 is a side view of the OLED array and the testing device of FIG.1, with an examination system in accordance with an exemplaryembodiment;

FIG. 4 is a side view of the OLED array, the testing device and theexamination system of FIG. 3, with a defect elimination system inaccordance with an exemplary embodiment;

FIG. 5 illustrates a method according to an exemplary embodiment;

FIG. 6 is a side view of an OLED array including internal layers andsealing layers in accordance with an exemplary embodiment; and

FIG. 7 illustrates a computer system according to an exemplaryembodiment.

DETAILED DESCRIPTION OF THE INVENTION

The method involves locating a defective sub-pixel by turning on theentire display near threshold of emission. The defective sub-pixel (orpixel, referred to hereinafter as a stuck-on OLED pixel) is destroyed byexposure to radiation that degrades the organic material in the stuck-onOLED pixel, rather than by ablation, which may destroy any sealinglayers that have been created. Performance of the method early in theproduction process, and in particular prior to the application of one ormore sealing, filtering or other layers, may reduce the limitations onthe features (e.g., wavelength, intensity, duration) of the light usedto degrade the organic materials in the defective OLED pixel, and/or mayincrease the effectiveness of the organic material degradation byreducing or eliminating interference with the radiation prior to theradiation contacting the defective OLED pixel. Alternatively, the methodmay be performed at the end of the manufacturing process.

A defect elimination system according to an exemplary embodiment allowsthe whole display to be dark, while only the defective stuck-on pixel(s)will be brightly lit up. This situation is achieved by energizing theOLED array above a threshold level and then reducing the energizingsignal below the threshold level. Once the pixel or sub-pixel isdetected and located with the help of a high power microscope it will bebrought into the center of the field of view with the help ofcross-wires. Light of suitable wavelength and intensity is used toprecisely irradiate the defective sub-pixel so that the organicmaterials in the OLED device are photo-chemically degraded. This in turnleads to reduced or no light emission from the irradiated sub-pixel.This method of eliminating a stuck-on pixel may be unique to the OLEDdevice since the organic materials are sensitive to short wavelengthlight and degrade rapidly under intense illumination. After eliminationof defective OLED pixels using the present method and/or system, whenthe OLED display is later lit up, dark regions exist where a shortwavelength light was illuminated for a certain period of time. Theexposure time can be reduced by increasing the dose of illumination.

The exposing operation may include taking care to avoid directing theultraviolet or visible light at OLED pixels situated adjacent to theOLED. The ultraviolet or visible light may be directed at the OLED byfocusing or other methods, and adjacent OLED pixels may be shielded fromthe ultraviolet or visible light by shielding. Additionally oralternatively, adjacent OLED pixels may have different characteristics,for instance when adjacent OLED pixels emit different color light, andmay be composed of different organic materials. In these situations, theradiation used to degrade the organic materials in the defective OLEDmay be selected to reduce the effect of any exposure to the radiationexperienced by the different organic material in the adjacent OLEDpixels.

One factor to be taken into consideration is that the illuminating lightneeds to go through a series of dielectric layers—both organic andinorganic. As such, the wavelengths of the illuminating light isimportant and should be chosen so that it does not damage the layers ofmaterials though which it passes to the reach the stuck-on pixel. Basedon the absorption spectrum of one of the key materials (emission layer)in the OLED device, visible light may be used having a wavelength of 405nm, 488 nm (which may be particularly well suited to green and bluecolor filters), and/or 551 nm (or 555 nm, either of which may beparticularly well suited to a red color filter). These wavelengths areparticularly interesting because they are in the visible region and donot cause any damage to the other layers in the OLED device. Anotherwavelength of the illuminating light may be effective ultraviolet lighthaving a wavelength of 365 nm. Although these are specific wavelengthsmentioned here, there could be a range of wavelengths that could beequally efficient in degrading the desired pixel. The choice of theilluminating wavelength also depends on the layers of dielectricmaterial that the light needs to pass through before impinging on thedefective sub-pixel. Furthermore, as discussed above, the wavelength,intensity and duration of the radiation selected to degrade the organicmaterial may be selected to reduce or eliminate the impact of any errantradiation received by adjacent pixels, especially in the situation inwhich the adjacent pixels include different organic materials and/ordifferent sensitivities with respect to radiation exposure.

The method may include, subsequent to the irradiation of the OLED,testing the array of OLED pixels to determine if the identified OLED hasbeen rendered inoperative. The testing of the array of OLED pixels todetermine if a stuck-on OLED has been rendered inoperative may includerepeating the operation of applying the energizing signal to the OLEDpixels, repeating the operation of reducing the energizing signalapplied to the at least one of the OLED pixels below the thresholdlevel, and determining if the stuck-on OLED of the array of OLED pixelsis emitting light. If the stuck-on OLED is emitting light, the methodmay include performing the operations of further irradiating the OLED tofurther degrade the organic material in the OLED, and further testingthe array of OLED pixels to determine if the identified OLED has beenrendered inoperative.

In a further irradiating operation according to an exemplary method, atleast one of a first intensity, a first time and a first wavelength of afirst radiation used in the irradiating operation is changed to at leastone of a second intensity, a second time and a second wavelength of asecond radiation.

Some exemplary methods include determining intensity, a time and awavelength of radiation sufficient to render an OLED of the OLED arrayinoperative by degrading organic material in the OLED. The organicmaterial in an OLED may include organo-metallic chelates (for example,Alq3), conjugated dendrimers, poly(p-phenylene vinylene) andpolyfluorene, or their derivatives, or any other appropriate organicmaterial. Degradation by irradiation of these or other organic materialsinvolve a photo-chemical reaction changing the chemical composition ofthe OLED. The determining operation is based on at least one of a firstdegradability of the organic material, a first absorption spectrum ofthe organic material, a second degradability of at least one surfacelayer of the OLED array, and a second absorption spectrum of the atleast one surface layer of the OLED array.

FIG. 1 is a plan view of a partially formed OLED array 100 connected todriver circuit 140 for purposes of testing and eliminating stuck-on OLEDpixels. During testing, driver circuit 140 is connected to the anode andcathode circuits of OLED array 100 in order to drive each OLED above anenergizing threshold, at which time the OLED becomes illuminated. Theenergizing signal may be applied to all of the OLED pixels, or fewerthan all of the OLED pixels in partially formed OLED array 100.Subsequently, driver circuit 140 is operated to reduce the voltage onthe anode and cathodes to below the threshold voltage level. Thereducing of the energizing signal below the threshold level may includemaintaining the energizing signal at a percentage of the threshold levelin which the percentage is less than 100%. The percentage may exceed90%, may exceed 75%, or may exceed 50%.

The threshold level as discussed herein is also referred to as a D.C.voltage, above which an OLED pixel emits light responsive to anadditional A.C. voltage. The variability of the additional A.C. voltageprovides a variable intensity output for the OLED pixel. The OLED pixelmay have 256 intensity levels within the additional A.C. voltage, with 1being the lowest intensity and 256 being a maximum intensity. In thiscase the D.C. voltage corresponds to a black output characterized as azero level. The threshold level discussed above would in this casecorrespond to level 1, below which the OLED pixel output should beblack.

FIG. 1 illustrates OLED array 100 being driven by driver circuit 140 ata level below the threshold voltage level after being driven above thethreshold voltage level. FIG. 1 illustrates that OLED array 100 includesthree stuck-on OLED pixels, or pixels, namely, stuck-on OLED pixels 110,120 and 130. Each of stuck-on OLED pixels 110, 120 and 130 continues tobe illuminated even though driver circuit 140 drives OLED array 100 at alevel below the threshold voltage level. Driver circuit 140 may beoperated at a level below the threshold voltage level but 1) above 90%of the threshold voltage level, 2) above 75% of the threshold voltagelevel, 3) above 50% of the threshold voltage level, or 4) above anyappropriate percentage of the threshold voltage level.

Alternatively, driver circuit 140 may operate as a current source tothereby energize the OLED pixels, and to subsequently reduce the currentto below a threshold energizing level.

FIG. 2 is a plan view of OLED array 100 after performance of anoperation to eliminate stuck-on OLED pixels. Irradiating stuck-on OLEDpixels 110, 120 and 130 with radiation sufficient to degrade the organicmaterial therein causes the OLED pixels to become inoperative.Therefore, application of a voltage or current above a threshold levelby driver circuit 140 causes all of the OLED pixels in OLED array 100 toilluminate, except stuck-on OLED pixels 110, 120 and 130. Therefore,each of stuck-on OLED pixels 110, 120 and 130 remains dark in FIG. 2,while the remainder of OLED array 100 is illuminated. Though this mayreduce the overall brightness of OLED array 100, driver circuit 140, orany other driver circuit connected to OLED array 100 during testing oroperation, may be configured to compensate for the loss of brightnessdue to the elimination of stuck-on OLED pixels 110, 120 and 130.

FIG. 3 is a side view of OLED array 100 and driver circuit 140. OLEDarray 100 is situated on x-y table 310, which may be operated to moveOLED array 100 laterally and longitudinally. Additionally, x-y table 310may be operated to move OLED array 100 vertically. Microscope 320 ispositioned above OLED array 100 and may be connected to light source330. Microscope 320 may be connected to light source 330 by a fiberoptic cable, or by any other appropriate method. Alternatively, lightsource 330 may be independent of microscope 320 but fixedly situatedadjacent or near to it. Microscope 320 may be any appropriate sensor fordetecting an illuminated OLED pixel, including an array of lightsensors. Microscope 320 and light source 330 may also be arranged tomove laterally and longitudinally, and possibly also vertically, inaddition to or instead of the movement provided by x-y table 310.Microscope 320 may be connected to a processor and adapted to identifythe location of stuck-on OLED pixels 110, 120 and 130. Alternatively oradditionally, x-y table 310 may also provide location information to aprocessor to identify stuck-on OLED pixels 110, 120 and 130.

FIG. 4 is a side view of OLED array 100, driver circuit 140, x-y table310, microscope 320, and light source 330. Also shown in FIG. 4 isdefect elimination system 400, which may be a radiation source, adaptedto project radiation 410 in a narrow beam onto the surface of OLED array100. Defect elimination system 400 may be arranged to move laterally andlongitudinally, and possibly also vertically, in addition to or insteadof the movement provided by x-y table 310. Defect elimination system 400may be adapted to project radiation 410 in a beam sufficiently narrow toreduce or eliminate any degradation of OLED pixels situated adjacent tostuck-on OLED pixels 110, 120 and 130. Radiation 410 may be variablewith respect to frequency, time and intensity in order to effectivelydegrade the organic materials in the stuck-on OLED pixels 110, 120 and130.

FIG. 5 illustrates method 500 according to an exemplary embodiment.Method 500 starts at start circle 510 and proceeds to operation 520,which indicates to at least partially form the array of OLED pixels.Each OLED in the array formed includes organic material. From operation520 the flow in method 500 proceeds to operation 530, which indicates toapply an energizing signal to the OLED pixels. The energizing signalexceeds a threshold level. From operation 530 the flow in method 500proceeds to operation 540, which indicates to reduce the energizingsignal to the OLED pixels below the threshold level. From operation 540the flow in method 500 proceeds to decision 550, which asks whether anyof the OLED pixels are stuck-on. If the answer to decision 550 isaffirmative, the flow proceeds to operation 560, which indicates tolocate the stuck-on OLED in the OLED array. Operation 560 may includedetermining if an OLED is emitting light, determining a location of theOLED that is emitting light, and, if the OLED is emitting light, theOLED is identified as the identified OLED by the location. Fromoperation 560 the flow in method 500 proceeds to operation 570, whichindicates to irradiate the stuck-on OLED to degrade the organic materialin the OLED. From operation 570 the flow in method 500 proceeds back tooperation 530, which operates at this point the beginning of a test ofthe effectiveness of the defect elimination operation. If the answer todecision 550 is negative, the flow proceeds to operation 580, whichindicates to further process the array of OLED pixels. Furtherprocessing may include adding protective layers or sealing layers to theOLED array. The sealing layers for the OLED array may be organic orinorganic. Additionally or alternatively, color filters may be addedduring this further processing, after the elimination of stuck-on OLEDpixels. From operation 580, the flow proceeds to end circle 590.

FIG. 6 is a side view of a complete OLED array 600 including OLED layer610 and various other layers in accordance with an exemplary embodiment.OLED array 100 discussed above in regard to the FIGS. 1-4 may includesome or all of the layers of complete OLED array 600. OLED layer 610includes stuck-on OLED pixels 110, 120 and 130. Layer 620 is arranged onthe bottom of complete OLED array 600, and may include Al₂O₃, which mayseal the OLED, reflect light output from the OLED layer 610 and/oroperate as a cathode or anode for OLED layer 610. Layer 620 may bearranged on another layer which provides a substrate, drive circuitryand/or any other appropriate function. Layer 630 arranged above layer620 and directly below OLED layer 610 may include parylene, which mayprovide the function of sealing OLED layer 610. Layer 640 arranged aboveOLED layer 610 may include parylene, which may be deposited in a thinfilm by vapor deposition, and may provide the function of sealing OLEDlayer 610. Layer 640 may be UV sensitive, and in particular may besensitive to UV light of less than 365 nm wavelength. Therefore, layer640 may be deposited after the elimination of defective OLED pixelsusing the method, or the wavelength of light used to eliminate the OLEDpixels may be determined in consideration of the effect on this layer,and in particular may be selected to be equal to greater than 365 nmwavelength. Layer 650 arranged above layer 640 may include SiO₂, whichmay be deposited by any appropriate method. Layer 650 may provide atransparent cathode or anode for controlling OLED layer 610.

Layer 660 arranged above layer 650 may be a color filter, which mayinclude filter sections 662, 664 and 666. Filter sections 662, 664 and666 are shown in only a small section of layer 650, but may fill theentire width of layer 660. Filter sections 662, 664 and 666 maycorrespond to red, blue and green filters, in no particular order otherthan forming a regular pattern within layer 660. Each filter section maycorrespond to a particular OLED, so that energizing the particular OLEDcauses light to be filtered through the particular filter section. Layer660 may be deposited by any appropriate method. Alternatively, layer 660may not be included in the layers of complete OLED array 600 if the OLEDarray is used to only emit a single color of light, or if different OLEDpixels that emit different colors of light are included in OLED layer610.

Layer 670 arranged above layer 660 may include glue or another adhesivefor attaching a glass or other final sealing material. Layer 670 may bedeposited by any appropriate method. Layer 680 arranged above layer 670may include glass, which may be attached mechanically to the glue oflayer 670 while the glue is tacky. Layer 680 may provide the function ofsealing the OLED array in order to prevent contamination of the OLEDpixels in OLED layer 610, as well as preventing the degradation of anyother components.

The method for manufacturing an organic light emitting diode (OLED)array may include, subsequent to the irradiation of the OLED, applying asurface layer to the array of OLED pixels. Any of the layers shown inFIG. 6 that are not present at the time of the identification andirradiation steps for eliminating stuck-on OLED pixels may be appliedafter that process to form complete OLED array 600. The layers incomplete OLED array 600 may be deposited or arranged in any appropriatemanner, including vacuum deposition, thermal evaporation, printing,and/or spin coating.

FIG. 7 illustrates a computer system according to an exemplaryembodiment. Computer 700 can, for example, operate driver circuit 140,x-y table 310, microscope 320, light source 330, or defect eliminationsystem 400. Additionally, computer 700 can perform the steps describedabove (e.g., with respect to FIG. 5). Computer 700 contains processor710 which controls the operation of computer 700 by executing computerprogram instructions which define such operation, and which may bestored on a computer-readable recording medium. The computer programinstructions may be stored in storage 720 (e.g., a magnetic disk, adatabase) and loaded into memory 730 when execution of the computerprogram instructions is desired. Thus, the computer operation will bedefined by computer program instructions stored in memory 730 and/orstorage 720 and computer 700 will be controlled by processor 710executing the computer program instructions. Computer 700 also includesone or more network interfaces 740 for communicating with other devices,for example other computers, servers, or websites. Network interface 740may, for example, be a local network, a wireless network, an intranet,or the Internet. Computer 700 also includes input/output 750, whichrepresents devices which allow for user interaction with the computer700 (e.g., display, keyboard, mouse, speakers, buttons, webcams, etc.).One skilled in the art will recognize that an implementation of anactual computer will contain other components as well, and that FIG. 7is a high level representation of some of the components of such acomputer for illustrative purposes.

While only a limited number of preferred embodiments of the presentinvention have been disclosed for purposes of illustration, it isobvious that many modifications and variations could be made thereto. Itis intended to cover all of those modifications and variations whichfall within the scope of the present invention, as defined by thefollowing claims.

I claim:
 1. A method for manufacturing an organic light emitting diode(OLED) array comprising OLED pixels, comprising: at least partiallyforming the OLED array, each OLED pixel in the OLED array includingorganic material and being responsive to an energizing signal exceedinga threshold level to energize same; applying the energizing signal to atleast one of the OLED pixels, the energizing signal exceeding thethreshold level; reducing the energizing signal applied to the at leastone of the OLED pixels below the threshold level; identifying at leastone the OLED pixels as a stuck-on OLED pixel that continues to remainenergized after the signal is reduced below the threshold level; andrendering the stuck-on OLED inoperative by degrading the organicmaterial in the active portion of the stuck-on OLED pixel throughirradiation of the stuck-on OLED, wherein the step of reducing theenergizing signal the threshold level includes maintaining theenergizing signal at the threshold level, wherein the percentage is lessthan 100% and exceeds 50%.
 2. The method of claim 1, further comprising,subsequent to the irradiation of the stuck-on OLED pixel, applying asurface layer to the OLED array.
 3. The method of claim 1, wherein theenergizing signal is applied all of the OLED pixels.
 4. The method ofclaim 1, wherein the identifying operation includes: determining if anOLED pixel is emitting light; determining a location of the OLED pixelthat is emitting light; and if the OLED pixel is emitting light, theOLED pixel is identified as the stuck-on OLED pixel by the location. 5.The method of claim 1, wherein the irradiating of the stuck-on OLEDpixel to degrade the organic material in the stuck-on pixel includesdirecting one of ultraviolet and visible light at the stuck-on OLEDpixel.
 6. The method of claim 5, further comprising: selecting anintensity, a time and a wavelength of the one of the ultraviolet andvisible light sufficient to render an OLED pixel of the OLED arrayinoperative by degrading organic material in the OLED pixel, theselecting operation being based on at least one of a first degradabilityof the organic material, a first absorption spectrum of the organicmaterial, a second degradability of at least one surface layer of theOLED array, and a second absorption spectrum of the at least one surfacelayer of the OLED array; wherein the selected intensity, the selectedtime and the selected wavelength of the one of the ultraviolet andvisible light determine the one of the ultraviolet and visible lightdirected at the stuck-on OLED pixel.
 7. The method of claim 1, furthercomprising, subsequent to the irradiation of the stuck-on OLED pixel,testing the OLED array to determine if the stuck-on OLED pixel has beenrendered inoperative.
 8. A method for manufacturing an organic lightemitting diode (OLED) array comprising OLED pixels, comprising: at leastpartially forming the OLED array, each OLED pixel in the OLED arrayincluding organic material and being responsive to an energizing signalexceeding a threshold level to energize same; applying the energizingsignal to at least one of the OLED pixels, the energizing signalexceeding the threshold level; reducing the energizing signal applied tothe at least one of the OLED pixels below the threshold level;identifying at least one the OLED pixels as a stuck-on OLED pixel thatcontinues to remain energized after the signal is reduced below thethreshold level; and irradiating the stuck-on OLED pixel to degrade theorganic material in the stuck-on OLED pixel, wherein the reducing of theenergizing signal below the threshold level includes maintaining theenergizing signal at a percentage of the threshold level, wherein thepercentage is less than 100% and exceeds 90%.
 9. A method formanufacturing an organic light emitting diode (OLED) array comprisingOLED pixels, comprising: at least partially forming the OLED array, eachOLED pixel in the OLED array including organic material and beingresponsive to an energizing signal exceeding a threshold level toenergize same; applying the energizing signal to at least one of theOLED pixels, the energizing signal exceeding the threshold level;reducing the energizing signal applied to the at least one of the OLEDpixels below the threshold level; identifying at least one the OLEDpixels as a stuck-on OLED pixel that continues to remain energized afterthe signal is reduced below the threshold level; and irradiating thestuck-on OLED pixel to degrade the organic material in the stuck-on OLEDpixel, wherein the reducing of the energizing signal below the thresholdlevel includes maintaining the energizing signal at a percentage of thethreshold level, wherein the percentage is less than 100% and exceeds75%.
 10. A method for manufacturing an organic light emitting diode(OLED) array comprising OLED pixels, comprising: at least partiallyforming the OLED array, each OLED pixel in the OLED array includingorganic material and being responsive to an energizing signal exceedinga threshold level to energize same; applying the energizing signal to atleast one of the OLED pixels, the energizing signal exceeding thethreshold level; reducing the energizing signal applied to the at leastone of the OLED pixels below the threshold level; identifying at leastone the OLED pixels as a stuck-on OLED pixel that continues to remainenergized after the signal is reduced below the threshold level; andirradiating the stuck-on OLED pixel to degrade the organic material inthe stuck-on OLED pixel, wherein the reducing of the energizing signalbelow the threshold level includes maintaining the energizing signal ata percentage of the threshold level, wherein the percentage is less than100% and exceeds 50%.
 11. A method for manufacturing an organic lightemitting diode (OLED) array comprising OLED pixels, comprising: at leastpartially forming the OLED array, each OLED pixel in the OLED arrayincluding organic material and being responsive to an energizing signalexceeding a threshold level to energize same; applying the energizingsignal to at least one of the OLED pixels, the energizing signalexceeding the threshold level; reducing the energizing signal applied tothe at least one of the OLED pixels below the threshold level;identifying at least one the OLED pixels as a stuck-on OLED pixel thatcontinues to remain energized after the signal is reduced below thethreshold level; and irradiating the stuck-on OLED pixel to degrade theorganic material in the stuck-on OLED pixel further comprising,subsequent to the irradiation of the stuck-on OLED pixel, testing theOLED array to determine if the stuck-on OLED pixel has been renderedinoperative, wherein the testing of the OLED array to determine if thestuck-on OLED pixel has been rendered inoperative includes: repeatingthe operation of applying the energizing signal to the at least one ofthe OLED pixels; repeating the operation of reducing the energizingsignal applied to the at least one of the OLED pixels below thethreshold level; and determining if the stuck-on OLED pixel of the OLEDarray is emitting light.
 12. The method of claim 11, wherein, if thestuck-on OLED pixel is emitting light, performing the operations of:further irradiating the stuck-on OLED pixel to further degrade theorganic material in the stuck-on OLED pixel; and further testing theOLED array to determine if the stuck-on OLED pixel has been renderedinoperative.
 13. The method of claim 12, wherein at least one of a firstintensity, a first time and a first wavelength of a first radiation usedin the irradiating operation is changed to at least one of a secondintensity, a second time and a second wavelength of a second radiationused in the further irradiating operation.